Heat>>passing slide on bunsen burner to prevent discarding of smear while staining Methanol >>better than heat , prevents liquid specimens from washing off, clearer bg

Labs Revision Flashcards by soad auf

Microorganisms multiply themselves in a culture media

Cultivation

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Culture media contains

Water
Carbon source
Nitrogen source
Buffer
Mineral source

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Culture media acc to purpose

Slant»storage of culture
Deep»gas requirements/motility
Plate»pure isolations/ observe biochemical reactions

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Culture media acc to nutritional components

Defined
Complex
Synthetic

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Acc to physical state

Liquid/ semi solid/ solid

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Acc to application

General purpose
Enriched> blood agar
Slective
Differential> MacConkey

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Isolation techniques

Streaking
Pour plate
Spread plate

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Determining microbial count

Turbidity
Plate count

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Calculating CFU

No.of colonies*dilution/ volume

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Colony identification

Shape/texture/height/color/consistency

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Microscopic identification

Simple stain
Gram stain
Acid fast
Special(endospore)

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Why stain

To differentiate microorganisms from their environment
Detailed observation
Different type differentiation

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Simple vs differential staining

1 solution to fixed smear- visualise morphology
Several reagents- distinguish cellular somponenets

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Smear preparation

Thin white film

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Fixation types

Heat»passing slide on bunsen burner to prevent discarding of smear while staining
Methanol&raquo_space;better than heat , prevents liquid specimens from washing off, clearer bg

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Stain types

Simple» positive(organism stained)/ negative(background stained)
Differential»gram staining(peptidoglycan)/ acid fast(wax like cell wall)
Special&raquo_space;endospore
Capsule staining»

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Gram staining

Gram +ve purple
Gram -ve pink/ red
Fixation - Crystal violet 30 sec (primary stain) - iodine 60 sec (mordant) - alcohol 10 sec (decolouriser& dehydrate peptidoglycan )- counter 1 mins stain(safranin)

Acid fast

Carbol fuchsin
Steam(loosen waxy layer to let stain in)
Decolouriser
Methylene blue
Acid fast> red
Non> blue

Why are spores resistant
Dyed with

High calcium and dipicolinic acid
Malachite green+ steam+safranin

Capsule staining
Why difficult

Capsules are water soluble , maybe removed with vigorous washing
Non ionic so dyes will not adhere to it

Physiological tests

Fermentation (MacConkey agar / Mannitol salt agar/ phenol red broth)
Hydrolysed products test (urease test/ catalase test)

Macconkey agar
Results

Gram -ve and lactose fermenting
Bile salts that inhibit gram +ve
Crystal violet
If not lactose then peptone
E.coli-klebisiella
Ph gets low red/pink colonies(lactose fermenting)

Mannitol salt agar

Phenol red
Selective for staphylococcus due to salt conc. NaCl
Ph gets low, yellow colour and or growth

Phenol red brith

Carbohydrate fermenter
Phenol red
Gas trapped in durham tube and or yellow colour

Urease

Urease enzyme Phenol red Red, bright colour

Catalase

Catalase enzyme production Bubbles

Dimorphic appearance is important for Change acc to

Infectivity and surviving diverse environments Temp/nutrients 25 mold 37 yeast

Dimorphic fungi examples

Histoplasma capsulatum>>lung disease histoplasmosis Candida albicans>vaginal yeast infections, oral thrush,candidiasis of skin

Culturing of fungi

Bacterial media>negative,less effective Fungal media> sabouraud dextrose agar/mycobiotic/germ tube test/urease test

Conidia names acc to size

Macroconidia Microconidia

Inappropriate usage of antibiotics leads to

Increased levels of antibiotic resistance by exerting selective pressure

Antimicrobial tests

Dilution tests>>min conc of antibiotic to control infection Broth dilution method>>micro (96 well)or macro (2ml)dilution,2 fold dilutions in liquid growth medium Agar dilution method>>different conc of antimicrobial into agar 2 fold then inoculation Disk diffusion>>kirby bauer,MHA plate, disk with antimicrobial on agar

MIC

Minimum inhibition conc Lowest conc of antimicrobial that inhibits bacterial growth

Bacterial suspension should be equivalent to..... this is done by matching that turbidity

0.5 McFarland standards

Growth medium that is commonly used for antibiotic suspectability tests and allows for even diffusion of the antibiotic

Mueller hinton plate MH

Algae are

Protist Uni or multicellular

Cell walls of algae... They are

Cellulose Photosynthetic

Classification of algae Brown

Brown >>multi/known as kelps which are long and tough/non motile/ reproductive cells have 2 flagella/cooler marine water/focus/macrocytsis/ have fucoxanthin

Red algae

Red>>multi/made of threads forming flat sheets/ non motile Attached to rocks Phycoerthrin Some ansorb calcium carbonate to their cell walls Chondrus Polysiphonia

Antibiotics

Zithromycin, nystatin, ciprofloxacin

Green algae

Uni or multi Colonial Have flagella Chlorella/chlamydomonas